Since the session videos will be online after the conference for registered Apple developers (that's what they did last year - setting a new Google I/O-pressured precedent), I think that leaves the sessions you really want to go to, Labs, networking, socializing.

The sessions. All of them are top-notch. Learn how to write code like an Apple engineer or think like one. They all know how to present and they all are happy to be there.

The Labs are unbelievable. You come with your thorniest bug/problem to the appropriate section and an Apple engineer will sit down with you to figure it out. You might have to wait a while but they will bring in other team members, if you have a particularly thorny issue.

When it comes to networking/socializing - just waiting in line for sessions/talking to people next to me - I met people who had written top-selling iPad/iPhone and/or well-known apps.

Oh, and partying. That is almost like networking but with full bar service.

Good luck and congratulations to those going, it's like no other technical conference.